Ni-doped germanium clusters have been systematically investigated by using the density functional approach. The growth-pattern behaviors, stabilities, charge transfer, and polarities of these clusters are discussed in detail. Obviously different growth patterns appear between small-sized Ni-doped germanium clusters and middle- or larger-sized Ni-doped germanium clusters. The Ni-convex or substituted Ge-n frames for small-sized clusters as well as Ni-concaved or encapsulated Ge-n frames for middle- or large-sized clusters are dominant growth patterns. The calculated fragmentation energies manifest that the magic numbers of stabilities are 5, 8, 10, and 13 for Ni-doped germanium clusters; the obtained relative stabilities exhibit that the Ni-encapsulated Ge-10 cluster is the most stable species of all different-sized clusters, which is in good agreement with available experimental observations of CoGe10-. Natural population analysis shows that different charge-transfer phenomena depend on the sizes of the Ni-doped Ge-n clusters. Additionally, the properties of frontier orbitals and the polarities of Ni-doped Ge-n clusters are also discussed.